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86 mustang lx 3.8 no fire

Running fine, shit it off and after 4-5 days the battery went dead(draw on it somewhere, maybe bad alt)

Swapped batt for another one that wasn’t much better, crank and fired up running VERY badly. Wouldn’t start because this batt was junk too. Hooked up a boost, started and ran fine, unhook a cable and runs like crap, same as before. Cable on/off/on/off and engine runs fine/crappy/fine /crappy.

Put a good charged battery and rolls over fast but no fire??
Injectors not squirting.
Pour some gas down the throat and not even a kick.
Pull coil wire off cap and stick a brand new plug in, nothing.

So, I have no fire from the coil and the injectors aren’t firing.(cfi type)

12v at coil, grounded the negative side and coil sparks, coil not bad.

Tfi??
Dist itself??

Head to the junkyard tomorrow to see if I can find one, don’t want to order a new distributor and “change parts until it runs”.

Anyone have any ideas what I should check next?? Only correlation I see between inj not firing and coil not firing is the distributor which runs both.

Anyone….?……
 
Well, put on a new tfi module and nothing. The test light on the neg side of the coil is not pulsing when cranking. It wasn’t pulsing before and according to YouTube guys, it’s supposed to pulse or flicker when cranking.
Hal effect sensor inside the dist bad?
This is starting to irritate me
 

broncojunkie

Well-Known Member
Sorry about the late reply. I had read your post but have been dealing with a new position at work and things have been hectic, to say the least lol!

The local parts stores that have been around for several years should have a tester to bench test these modules. That way, you won't have to buy one on a hunch. Have them run the test at least 3 times. It needs to consistently pass in order to be considered working. After a couple tests, I believe it warms up enough to tell you if it's breaking down due to heat. If you get a new one, have them test that too. The test just takes a few seconds (and probably a couple minutes to get it hooked up and find the right plug connector).

I had an 86 3.8 but don't remember the setup. Is it throttle body injection (cfi)?
 
Last edited:
Thanks for responding!
Yes it is cfi. Next test is to see if it has a pip signal I guess. I have another harness from a 98 351 f350 so I can cut the wires off and just use the distributor plug with test leads on the wires.
Doing some searching I found the pip goes out the top wire to the computer and then returns in the bottom one?? Is that right?
Or is there a proper test to do?

Thanks!
 
Ok, so I found out that the distributor plug with the 6 wires is the following;
Blue-pip signal from reluctor
Yellow-spout
Red with lot blue-cranking power (12v)
Red with green-run power (12v)
Yellow-coil control (neg side of coil)
Brown(or black with orange?) ground

Tomorrow I’m going to pull the spout plug and see if it starts and if not, confirm there is power during cranking and during run position. Pretty sure there is and I think my issue is no pip signal so the coil isn’t firing and because the rev isn’t getting a pip signal, it doesn’t know the engine is cranking so it’s not firing the injectors.

That’s my theory at 12:04 am.. we’ll see tomorrow I guess.
 
Well, I was right… partially. I hooked up a 351 distributor to the harness with the original 3.8 module that I thought was gone. Spun the distributor by hand and we have spark!
Unfortunately, the injectors are not firing. If I dump gas down the “carb” the engine fires up and runs smooth so ign side is good.

So now, fuel pump is running steady and the injectors aren’t firing.(I have 3/4 tank of gas)
Looking like a eec issue
 

broncojunkie

Well-Known Member
I think you're on the right track. I know the efi cars have a ground wire for the injectors. Iirc, it's an orange wire that goes from the injector harness to the firewall. It's been known to cause injector problems. They also have an ecu relay. You might want to check and see if yours is set up that way. Find that relay and check it, if it exists.
 
Thanks for the response! I’ll do more looking see if I can find the relay.
I’m assuming if I need a computer, it would be specific, as in, I need a 86 with cfi 3.8/auto and not a more common 86 5.0/auto.(which are everywhere)

Anybody know for sure on whether another computer would work or if it must be exact?
 
Well, pulled the computer and opened it, looks new, no burnt smell, etc. put it back in and fire with the spout unhooked and no fire when the spout is hooked up.
Injectors are still not firing either.

Getting frustrated
 
Ok…. For anyone else in this position, I found the alternator was OVER charging, which blew up the computer. Also, the reluctor in the distributor was bad but the TFI modules was good!
Here’s a video…
First video

Second video
 
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